Depending on which version of perl you got, you will get one of the following from perldoc -q 500

My CGI script runs from the command line but not the browser. (500 Server Error)
Several things could be wrong. You can go through the
"Troubleshooting Perl CGI scripts" guide at
http://www.perl.org/troubleshooting_CGI.html
If, after that, you can demonstrate that you've read the FAQs
and that your problem isn't something simple that can be easily
answered, you'll probably receive a courteous and useful reply
to your question if you post it on
comp.infosystems.www.authoring.cgi (if it's something to do with
HTTP or the CGI protocols). Questions that appear to be Perl
questions but are really CGI ones that are posted to
comp.lang.perl.misc are not so well received.
The useful FAQs, related documents, and troubleshooting guides
are listed in the CGI Meta FAQ:
http://www.perl.org/CGI_MetaFAQ.html

older

My CGI script runs from the command line but not the browser. (500 Server Error)
If you can demonstrate that you've read the following FAQs and
that your problem isn't something simple that can be easily
answered, you'll probably receive a courteous and useful reply
to your question if you post it on
comp.infosystems.www.authoring.cgi (if it's something to do with
HTTP, HTML, or the CGI protocols). Questions that appear to be
Perl questions but are really CGI ones that are posted to
comp.lang.perl.misc may not be so well received.
The useful FAQs and related documents are:
CGI FAQ
http://www.webthing.com/tutorials/cgifaq.html
Web FAQ
http://www.boutell.com/faq/
WWW Security FAQ
http://www.w3.org/Security/Faq/
HTTP Spec
http://www.w3.org/pub/WWW/Protocols/HTTP/
HTML Spec
http://www.w3.org/TR/REC-html40/
http://www.w3.org/pub/WWW/MarkUp/
CGI Spec
http://www.w3.org/CGI/
CGI Security FAQ
http://www.go2net.com/people/paulp/cgi-security/safe-cgi.txt

This should be the first response to every question dealing with perl and error 500.
The 2nd response should be "where's the sourcecode?"